While in use, a laser beam is directed at the desired workpiece. For example, in laser welding, the workpiece would be the material being welded. There are periods, however, when laser beams are activated but are not directed at the workpiece, such as during laser beam alignment. Because laser beams can injure eyes and damage surrounding hardware during such periods, they must be captured and appropriately terminated in a laser beam dump. The use of a laser beam dump is particularly important in high-energy laser applications, given the potential damage high-energy laser beams can inflict on equipment and personnel.
One type of laser beam dump suitable for high-energy applications (such as kilowatt or megawatt laser output) includes a conical copper reflector within a cylindrical copper housing. The interior of the cylindrical copper housing is coated with absorbent material such as carbon or graphite so that laser energy reflected from the conical copper reflector is absorbed by the laser beam dump. After sustained use, the copper reflector and/or the laser beam dump surfaces may exhibit surface temperatures of several hundred degrees Celsius such that forced air or water cooling of the laser beam dump through cooling channels may be necessary.
The resulting weight of the required amount of copper and cooling apparatus makes copper laser beam dumps relatively heavy, making their use in certain applications problematic. For example, a relatively heavy laser beam dump is undesirable in airborne applications. Moreover, diffuse backscatter of laser energy from the copper reflector and the dump surfaces leads to the propagation of laser energy in unwanted directions. Such unwanted laser energy propagation is undesirable in low power and high power applications where the signal-to-noise ratio in associated detectors is important.
Accordingly, there is a need in the art for light-weight laser beam dumps that can terminate high-energy laser beams with a minimal amount of backscatter.